you mean that 535 automatic trans switich 3rd to 4th gear at that speed...my cars stumbles at that speed after coasting between 45-50 mph just about to accelarate sometimes multiple stumbles and then disappearsfor days..since i bought my 92 bmw535i with 90K i always had this problem that the car stumbles intermettently or misfires(i think) !! when traveling between 40-50mph. Does anyone experince the same, is there a service bulletin for this problem?